The invention relates to an electric motor drive mechanism, in particular a window control drive mechanism for a motor vehicle. Electric motor drive mechanisms are widely known and can be used especially in the automotive field for adjusting manifold vehicle components. This applies for instance to adjusting vehicle seats, windows and sun roofs, or also to adjusting mirrors. The drive mechanisms employed as a rule have an electric motor and a gear following it, as well as an electronic control and supply unit. This electronic unit is constructed on a circuit board that is accommodated in an electronics housing.
To determine position parameters of the actuating drive, sensor devices that are disposed on a sensor prong are typically used. These sensor devices interact with the rotating motor armature shaft and count the revolutions of the shaft. For this purpose, it is necessary that the sensor prong and the electronics connected to it be positionable as precisely as possible and fixable as securely as possible.
These two requirements make for a considerable outlay for assembly of the electronics, since by the previous assembly technology all the electronics along with the sensor device, and optionally in the brush holder, are screwed or clipped to the gear housing. The electronic unit is open toward the gear, so that in addition to the problem of positioning and fixation, a sealing problem arises.
The electric motor drive mechanism according to the invention has the advantage that the electronics housing can be connected to the drive mechanism securely and largely without play; the assembly is simplified substantially because the electronics housing need merely be slipped onto the guide rail of the gear housing, and exact positioning of the sensor device connected to the electronic unit, for determining position parameters of the drive mechanism, is made possible.
Advantageous refinements of the electric motor drive mechanism are possible.
For instance, it is advantageous if the guide rail, which is disposed either on the electronics housing or on the gear housing, extends substantially over the width of the electronics housing. As a result, binding of the electronics housing to the drive mechanism occurs over the maximum possible length; the electronic unit is optimally fixed, and a sensor prong attached to it can be positioned with high precision.
It is highly advantageous if the guide rail is embodied in rectangular shape. As a result, an ideal positive engagement with the counterpart guide and high strength of the electronics housing, both in the direction parallel to the motor armature shaft and in the radial direction, are achieved.
Along with this optimal guidance, which makes close production tolerances possible, assembly of the electronic unit is facilitated considerably, since it need merely be inserted into the drive mechanism via this guide mechanism.
A further advantage is that the electronics housing is already guided before the sensor prong dips into the recess of the brush holder. This additionally facilitates assembly of the electronic unit, and at the same time the risk of damage to the sensor device is minimized.
In a further advantageous feature of the electric motor drive mechanism, the guide rail has at least one central indentation, extending along the guide rail, in which indentation an also central, longitudinally extending protuberance of the counterpart guide is guided. This feature increases the precision of the guidance still further.
It is also advantageous if the inserted electronics housing can be secured with a securing means, in particular in the form of a screw. This is preferably disposed on the end of the guide rail remote from the motor armature shaft, at an angle of approximately 45xc2x0 to the motor armature shaft. As a result, not only can the play in the radial direction to the motor armature shaft axis be minimizedxe2x80x94as in conventionally. disposed securing means at an angle of 90xc2x0 to the motor armature shaftxe2x80x94in addition to the fixation in this radial direction, but at the same time a play-free fastening in the axial direction is made possible.
A further feature of the invention provides that the electronics housing is braced, opposite a pole pot of the electric motor, with a support pin disposed on the electronics housing. This support pin is received by a recess that is disposed in the brush holder, for instance, and offers an additional bracing option for the electronics housing. It therefore relieves the guide mechanism and furthermore minimizes the introduction of force into the sensor prong.
If this support pin has a chamfer, then the precise introduction of the support pin into the recess is facilitated.
A quite general advantage of the electric motor drive mechanism according to the invention is that the electronic unit is a completely separate part, which can be slipped onto various drive mechanisms universally. Because of the advantageous guide mechanism, a high degree of flexibility is achieved, since drive mechanisms and electronic units of the most various types can be combined with one another in a fundamentally arbitrary way. At little engineering effort or expense, along with substantially simpler assembly, better fixation of the electronics housing to the drive mechanism and a substantially more-precise positioning of the sensor prong, attached to the electronics housing, to the armature shaft of the drive mechanism are achieved.